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    <title>ctr_gram</title>
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    <center>Scilab Function</center>
    <div align="right">Last update : April 1993</div>
    <p>
      <b>ctr_gram</b> -  controllability gramian</p>
    <h3>
      <font color="blue">Calling Sequence</font>
    </h3>
    <dl>
      <dd>
        <tt>[Gc]=ctr_gram(A,B [,dom])  </tt>
      </dd>
      <dd>
        <tt>[Gc]=ctr_gram(sl)  </tt>
      </dd>
    </dl>
    <h3>
      <font color="blue">Parameters</font>
    </h3>
    <ul>
      <li>
        <tt>
          <b>A,B</b>
        </tt>: two real matrices of appropriate dimensions</li>
      <li>
        <tt>
          <b>dom</b>
        </tt>: character string (<tt>
          <b>'c'</b>
        </tt> (default value) or <tt>
          <b>'d'</b>
        </tt>)</li>
      <li>
        <tt>
          <b>sl</b>
        </tt>: linear system, <tt>
          <b>syslin</b>
        </tt> list</li>
    </ul>
    <h3>
      <font color="blue">Description</font>
    </h3>
    <p>
    Controllability gramian of <tt>
        <b>(A,B)</b>
      </tt> or <tt>
        <b>sl</b>
      </tt> (a <tt>
        <b>syslin</b>
      </tt> 
    linear system).</p>
    <p>
      <tt>
        <b>dom</b>
      </tt> character string giving the time domain : <tt>
        <b>"d"</b>
      </tt> for a
    discrete time system and <tt>
        <b>"c"</b>
      </tt> for continuous time (default case).</p>
    <h3>
      <font color="blue">Examples</font>
    </h3>
    <pre>

A=diag([-1,-2,-3]);B=rand(3,2);
Wc=ctr_gram(A,B)
U=rand(3,3);A1=U*A/U;B1=U*B;
Wc1=ctr_gram(A1,B1)    //Not invariant!
 
  </pre>
    <h3>
      <font color="blue">See Also</font>
    </h3>
    <p>
      <a href="equil1.htm">
        <tt>
          <b>equil1</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="obs_gram.htm">
        <tt>
          <b>obs_gram</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="contr.htm">
        <tt>
          <b>contr</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="cont_mat.htm">
        <tt>
          <b>cont_mat</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="cont_frm.htm">
        <tt>
          <b>cont_frm</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="contrss.htm">
        <tt>
          <b>contrss</b>
        </tt>
      </a>,&nbsp;&nbsp;</p>
    <h3>
      <font color="blue">Author</font>
    </h3>
    <p>S. Steer INRIA 1988</p>
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